What is the purpose of a posted speed limit sign?

A posted speed limit sign is designed to indicate the maximum speed allowed under ideal driving conditions. This means that while it provides a legal speed benchmark that drivers should not exceed, it also assumes that road conditions are optimal, including clear weather, good visibility, and a well-maintained road surface.

In situations where conditions are not ideal—like during inclement weather, heavy traffic, or road work—drivers are expected to adjust their speed accordingly, even if that means driving below the posted limit to maintain safety. Therefore, the presence of a speed limit sign is in place to promote safe driving practices by establishing a maximum threshold rather than suggesting it is the speed one must always travel.

The other options offered different interpretations of speed limit signs that are not their primary function. For instance, while some roads have minimum speed limits to keep traffic flowing, that is not the purpose of most speed limit signs. Similarly, while speed limits could suggest safe driving speeds under various conditions, they primarily designate a maximum allowable speed. A mandate for drivers to drive as fast as possible contradicts the overall intent of traffic regulations, which prioritize safety.